i have did sakura chase at least 3x in the past. from my personal experiences, can only start to get more accurate forecast on march.
especially when the southern part of japan like okinawa starts to bloom, you can estimate in 1-2 weeks time, the sakura season will start to move up northwards gradually. this is provided that there is no abrupt weather change like rain, or sudden temperature rise in the region as that will affect the timings.
from okinawa first bloom report, i will usually start looking at air tix. hotels i usually will booked during feb. always have backup plans for places to visit in case your main targeted location bloomed earlier. for example, if i targeted tokyo, i will put kyoto in the backup list, so if i failed to meet the timings for tokyo, kyoto will become the substitute.
do not be ambitious and wanna visit every single place especially cross over to another city like "i want tokyo 3 days and osaka 3 days'. you will usually spent hours and hours in a spot looking and exploring the beauty of the sakura because all looks the same yet each is so different. a gust of wind will send a very short lived moment of "sakura rain", or at different angle you will discovered a new feel to the viewing, you could even see a cat sleeping lazily on the tree branches.
there are just so many things happening. i could simply spent like half a day in shinjuku koen. once myself and a whole group of photographers were camping under a shidarezakura "weeping cherry tree" patiently waiting for it full bloom under the warm of the noon sun.
if you put so many places to visit into your list, i am pretty sure you will not discover the real magical feel of the season.
means osaka full bloom gone?! Wahhhhhhh T.T
